Can We Perform CT of the Appendix with Less Than 1 mSv? A De-escalating Dose-simulation Study

• Published in: European radiology 2018-05, Vol.28 (5), p.1826-1834
• Main Authors: Park, Ji Hoon, Jeon, Jong-June, Lee, Sung Soo, Dhanantwari, Amar C., Sim, Ji Ye, Kim, Hae Young, Lee, Kyoung Ho
• Format: Article
• Language: English
• Subjects: Abdomen; Adolescent; Adult; Adults; Appendicitis; Appendicitis - diagnosis; Appendix; Appendix - diagnostic imaging; Computed Tomography; Diagnostic Radiology; Diagnostic systems; Female; Humans; Imaging; Internal Medicine; Interventional Radiology; Male; Medicine; Medicine & Public Health; Neuroradiology; Radiation; Radiation Dosage; Radiographic Image Interpretation, Computer-Assisted - methods; Radiography, Abdominal - methods; Radiology; ROC Curve; Simulation; Tomography, X-Ray Computed - methods; Ultrasound; Young Adult; Young adults
• ISSN: 0938-7994; 1432-1084
• DOI: 10.1007/s00330-017-5159-3

Objectives To systematically explore the lowest reasonably achievable radiation dose for appendiceal CT using an iterative reconstruction (IR) in young adults. Methods We prospectively included 30 patients who underwent 2.0-mSv CT for suspected appendicitis. From the helical projection data, 1.5-, 1.0- and 0.5-mSv CTs were generated using a low-dose simulation tool and the knowledge-based IR. We performed step-wise non-inferiority tests sequentially comparing 2.0-mSv CT with each of 1.5-, 1.0- and 0.5-mSv CT, with a predetermined non-inferiority margin of 0.06. The primary end point was the pooled area under the receiver-operating-characteristic curve (AUC) for three abdominal and three non-abdominal radiologists. Results For the abdominal radiologists, the non-inferiorities of 1.5-, 1.0- and 0.5-mSv CT to 2.0-mSv CT were sequentially accepted [pooled AUC difference: 2.0 vs. 0.5 mSv, 0.017 (95% CI: -0.016, 0.050)]. For the non-abdominal radiologists, the non-inferiorities of 1.5- and 1.0-mSv CT were accepted; however, the non-inferiority of 0.5-mSv CT could not be proved [pooled AUC difference: 2.0 vs. 1.0 mSv, -0.017 (-0.070, 0.035) and 2.0 vs. 0.5 mSv, 0.045 (-0.071, 0.161)]. Conclusion The 1.0-mSv appendiceal CT was non-inferior to 2.0-mSv CT in terms of diagnostic performance for both abdominal and non-abdominal radiologists; 0.5-mSv appendiceal CT was non-inferior only for abdominal radiologists. Key points • For both abdominal and non-abdominal radiologists, 1.0-mSv appendiceal CT could be feasible. • The 0.5-mSv CT was non-inferior to 2.0-mSv CT only for expert abdominal radiologists. • Reader experience is an important factor affecting diagnostic impairment by low-dose CT.